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Scherer A, Yildirim B, Drescher M. The effect of the zero-field splitting in light-induced pulsed dipolar electron paramagnetic resonance (EPR) spectroscopy. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2023; 4:27-46. [PMID: 37904801 PMCID: PMC10583298 DOI: 10.5194/mr-4-27-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/13/2023] [Indexed: 11/01/2023]
Abstract
Laser-induced magnetic dipole (LaserIMD) spectroscopy and light-induced double electron-electron resonance (LiDEER) spectroscopy are important techniques in the emerging field of light-induced pulsed dipolar electron paramagnetic resonance (EPR) spectroscopy (light-induced PDS). These techniques use the photoexcitation of a chromophore to the triplet state and measure its dipolar coupling to a neighboring electron spin, which allows the determination of distance restraints. To date, LaserIMD and LiDEER have been analyzed with software tools that were developed for a pair of two S = 1 / 2 spins and that neglected the zero-field splitting (ZFS) of the excited triplet. Here, we explore the limits of this assumption and show that the ZFS can have a significant effect on the shape of the dipolar trace. For a detailed understanding of the effect of the ZFS, a theoretical description for LaserIMD and LiDEER is derived, taking into account the non-secular terms of the ZFS. Simulations based on this model show that the effect of the ZFS is not that pronounced in LiDEER for experimentally relevant conditions. However, the ZFS leads to an additional decay in the dipolar trace in LaserIMD. This decay is not that pronounced in Q-band but can be quite noticeable for lower magnetic field strengths in X-band. Experimentally recorded LiDEER and LaserIMD data confirm these findings. It is shown that ignoring the ZFS in the data analysis of LaserIMD traces can lead to errors in the obtained modulation depths and background decays. In X-band, it is additionally possible that the obtained distance distribution is plagued by long distance artifacts.
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Affiliation(s)
- Andreas Scherer
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Berk Yildirim
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Malte Drescher
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
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Zeng Z, Fichou Y, Vigers M, Tsay K, Han S. Illuminating the Structural Basis of Tau Aggregation by Intramolecular Distance Tracking: A Perspective on Methods. J Phys Chem B 2022; 126:6384-6395. [PMID: 35994024 DOI: 10.1021/acs.jpcb.2c02022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aggregation of the tau protein is central to several neurodegenerative diseases, collectively known as tauopathies. High-resolution views of tau tangles accumulated under pathological conditions in post-mortem brains have been revealed recently by cryogenic electron microscopy. One of the striking discoveries was that fibril folds are unique to and homogeneous within one disease family, but typically different between different tauopathies. It is widely believed that seeded aggregation can achieve structural propagation of tau fibrils and generate pathological fibril structures. However, direct molecular level measurement of structural evolution during aggregation is missing. Here, we discuss our perspective on the biophysical approaches that can contribute to the ongoing debate regarding the prion-like propagation of tau and the role of cofactors. We discuss the unique potential of double electron-electron resonance (DEER)-based intramolecular distance measurement, sensitive to two to several nanometers distances. DEER can track the structural evolution of tau along the course of aggregation from the completely disordered state, to partially ordered and highly ordered fibril states, and has the potential to be a key tool to elucidate the disease-specific tau aggregation pathways.
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Affiliation(s)
- Zhikai Zeng
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Yann Fichou
- CNRS, Chemistry and Biology of Membranes and Nanoobjects (CBMN) UMR 5348, Institut Europeen de Chimie et Biologie (IECB), University of Bordeaux, 33600 Pessac, France
| | - Michael Vigers
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Karen Tsay
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
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Chaudhry S, Wu Y, Cao Z, Li S, Canada JL, Gu X, Risko C, Mei J. Evolution of Chain Dynamics and Oxidation States with Increasing Chain Length for a Donor–Acceptor-Conjugated Oligomer Series. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Saadia Chaudhry
- Department of Chemistry, Purdue University West Lafayette, Indiana 47907, United States
| | - Yukun Wu
- Department of Chemistry, Purdue University West Lafayette, Indiana 47907, United States
| | - Zhiqiang Cao
- School of Polymer Science and Engineering, The University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States
| | - Shi Li
- Department of Chemistry & Center for Applied Energy Research (CAER), University of Kentucky, Lexington, Kentucky 40506, United States
| | - Jodie L. Canada
- Department of Chemistry & Center for Applied Energy Research (CAER), University of Kentucky, Lexington, Kentucky 40506, United States
| | - Xiaodan Gu
- School of Polymer Science and Engineering, The University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States
| | - Chad Risko
- Department of Chemistry & Center for Applied Energy Research (CAER), University of Kentucky, Lexington, Kentucky 40506, United States
| | - Jianguo Mei
- Department of Chemistry, Purdue University West Lafayette, Indiana 47907, United States
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Du H, Zhang L, Mao W, Zhao Y, Huang H, Xiao Y, Zhang Y, He X, Wang K. Ultrafine fluorene-pyridine oligoelectrolyte nanoparticles for supersensitive fluorescence sensing of heparin and protamine. Chem Commun (Camb) 2021; 57:8304-8307. [PMID: 34318803 DOI: 10.1039/d1cc01969d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A new fluorene-pyridine oligoelectrolyte (OFP) is rationally proposed and readily synthesized via a simple one-pot Sonogashira approach. Hence, an unexpectedly small cationic oligomer nanosensor (i.e. OFPNPs, ∼ 1.2 nm in diameter) was conveniently fabricated owing to the enhanced flexibility endowed by the meta-substituted pyridyl unit. Inspiringly, this facile nanoplatform with low cytotoxicity favors the ultrasensitive fluorescence assay for heparin and protamine with a detection limit (LOD, S/N = 3) as low as 1.2 ng mL-1 and 0.5 ng mL-1, respectively, involving heparin-induced aggregation of OFPNPs through electrostatic interaction or competitive rebinding of protamine to heparin.
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Affiliation(s)
- Huifeng Du
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, P. R. China.
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Wollmann J, Kahle FJ, Bauer I, Köhler A, Strohriegl P. Versatile Approach to Well-Defined Oligofluorenes and Polyfluorenes with Low Dispersity. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01887] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Sherck N, Webber T, Brown DR, Keller T, Barry M, DeStefano A, Jiao S, Segalman RA, Fredrickson GH, Shell MS, Han S. End-to-End Distance Probability Distributions of Dilute Poly(ethylene oxide) in Aqueous Solution. J Am Chem Soc 2020; 142:19631-19641. [DOI: 10.1021/jacs.0c08709] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nicholas Sherck
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Thomas Webber
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Dennis Robinson Brown
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Timothy Keller
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Mikayla Barry
- Department of Materials, University of California, Santa Barbara, California 93106, United States
| | - Audra DeStefano
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Sally Jiao
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Rachel A. Segalman
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Materials, University of California, Santa Barbara, California 93106, United States
| | - Glenn H. Fredrickson
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Materials, University of California, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
| | - M. Scott Shell
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Songi Han
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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